JP2021534461A - Mettrozi device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for determining in-plane distortion (IPD) of an entire substrate including a plurality of patterned regions. SOLUTION: The method acquires intra-regional data showing a local stress distribution over one of a plurality of patterned regions and shows the overall stress distribution of the entire substrate based on the intra-regional data. The inter-regional data is determined, and the IPD of the entire substrate is determined based on the inter-regional data. [Selection diagram] FIG. 8

Description

This application is filed August 22, 2018 and claims the priority of EP application 18190150.5, which is incorporated herein by reference in its entirety.

The present invention relates to a metric device for determining in-plane strain (IPD) of an entire substrate, such as a semiconductor wafer, and related methods.

A lithography device is a machine constructed to apply a desired pattern on a substrate. Lithography equipment can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic device, for example, a layer of a radiation sensitive material (resist) provided on a substrate (eg, a wafer) with a pattern (often also referred to as a "design layout" or "design") in a patterning device (eg, a mask). Can be projected on. The projected pattern may form part of the process of manufacturing the structure on the substrate.

To project the pattern onto the substrate, the lithography equipment can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be formed on the substrate. Typical wavelengths currently in use are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm. Using a lithographic device that uses extreme ultraviolet (EUV) radiation with wavelengths in the range of 4 to 20 nm, such as 6.7 nm or 13.5 nm, on a substrate than, for example, a lithographic device that uses radiation at a wavelength of 193 nm. Small features can be formed in.

Low-k1 lithography can be used to process features with dimensions smaller than the classical resolution limits of lithographic equipment. In such a process, the resolution equation can be expressed as CD = k1 × λ / NA. Where λ is the wavelength of the radiation used, NA is the numerical aperture of the projection optical system of the lithography equipment, and CD is the “critical dimension” (generally the smallest feature size printed, but in this case half pitch). , K1 is an empirical resolution coefficient. In general, the smaller k1 is, the more difficult it is to reproduce on a substrate a pattern similar in shape and dimensions planned by the circuit designer to achieve a particular electrical function and performance. To overcome these difficulties, sophisticated fine-tuning steps can be applied to the lithography projector and / or the design layout. These include, but are not limited to, NA optimization, customized irradiation schemes, use of phase shift patterning devices, optical proximity effect correction (OPC, sometimes also referred to as "optical and process correction") and other designs. Includes various layout optimizations, or other methods commonly defined as "resolution enhancement techniques" (RET). Alternatively, strict control loops for controlling the stability of the lithography equipment can be used to improve pattern reproduction at low k1.

The overall measurement quality of a lithography parameter with a particular target is at least partially determined by the measurement recipe used to measure this lithography parameter. The term "board measurement recipe" may include one or more parameters of the measurement itself, one or more parameters of one or more patterns measured, or both. For example, if the measurement used in the substrate measurement recipe is a diffraction-based optical measurement, the parameters of the measurement may be for the wavelength of the radiation, the polarization of the radiation, the angle of incidence of the radiation, the substrate, the pattern on the substrate. It may include the direction of radiation and so on. One of the criteria for selecting a measurement recipe may be, for example, the sensitivity of one of the measurement parameters to processing variation. More examples are US Patent Application US2016-0161863, and unpublished US Patent Application No. 15 / 181,126, which are incorporated herein by reference in their entirety.

The substrate may include multiple patterned areas, which may also be referred to as a die or field. In-field stress is one of the major overlay challenges for manufacturers of ICs, especially 3D NAND ICs. High in-field stress levels can be attributed to the 3D NAND architecture. This requires the deposition of a large number of two layers, for example nitride-oxide-nitride-oxide (NONO). Moreover, when exposing patterned areas, the stress in the field may not be uniform across the exposed field. Each die may contain a memory array with high stress levels and peripherals (such as logic) that may have low stress levels. This can result in very high-order distortion patterns across the field.

In-field stress causes serious in-field overlay errors, but it is possible to significantly correct these errors. However, in-field stress can also result in higher-order inter-field distortion patterns (ie, between multiple dies) that cannot be corrected by currently available wafer alignment models. In addition, higher-order interfield distortion patterns are the current overlay mettroge because most overlay measurement targets are located in the scribe lane, whereas most distortion occurs in the product area (such as between scribe lanes). It is very difficult to characterize.

According to one aspect of the invention, it is a method for determining in-plane distortion (IPD) of an entire substrate including a plurality of patterned regions, which is localized over one of the plurality of patterned regions. The intra-regional data showing the stress distribution is acquired, the inter-regional data showing the overall stress distribution of the entire substrate is determined based on the intra-regional data, and the IPD of the entire substrate is determined based on the inter-regional data. The method is provided.

Optionally, it further comprises acquiring intra-regional data based on measurements of one or more geometric properties of the substrate.

Optionally, one or more measured geometric properties include the out-of-plane shape of the substrate.

Optionally, acquiring intra-regional data further comprises determining the quadratic derivative of one or more measured geometric properties.

Optionally, determining the quadratic derivative of one or more measured geometric properties is a quadratic derivation of one or more geometric properties measured along a particular planar direction. It involves determining a function and / or determining a measured mixed quadratic derivative along one or more geometric properties along two directions that are not parallel to the plane.

Optionally, retrieving intra-regional data further comprises averaging the quadratic derivatives determined across multiple patterned regions.

Optionally, intra-regional data is acquired based on the layout of the pattern within the patterned region.

Optionally, the layout of the pattern is determined based on one or more of the field layout, die layout, chip layout, and reticle layout.

Optionally, intra-regional data is acquired based on material properties and / or pattern features associated with the substrate.

Optionally, intra-regional data is retrieved based on the data associated with the stack of features that form at least part of the pattern.

Optionally, in-region data is acquired based on measurements of in-plane displacement of one or more features that form at least a portion of the pattern.

Optionally, the finite element method is used to determine the interregional data based on the intraregional data.

Optionally, it further comprises using the finite element method to determine out-of-plane distortion (OPD) and IPD based on in-region data.

Optionally, the OPDs and IPDs determined based on the results of the finite element method further include adding to a library containing multiple OPDs for IPDs for a set of predefined top film stresses.

Optionally, it further comprises determining the IPD of the additional substrate based on the geometric properties of one or more of the additional substrates and the measurement of OPD and IPD in the library.

Optionally, one or more of the geometric properties of the additional substrate will include the OPD shape of the additional substrate, and determining the IPD of the additional substrate will allow the OPD shape of the additional substrate to be among the multiple OPDs in the library. Includes adapting to one or more of the above, and determining the IPD based on the IPD corresponding to one or more of the OPDs.

Optionally, determining the IPD of an additional substrate involves adapting the OPD shape of the additional substrate to multiple OPDs in the library, each of which is weighted in conformance to determine the IPD. Includes summing the IPDs corresponding to the plurality of OPDs in the fit, weighted based on the weights of the plurality of OPDs.

It further comprises one or both of selectively applying corrections to the lithography equipment based on the determined IPD and controlling the alignment of the substrate within the lithography equipment based on the determined IPD.

Optionally, the region comprises a field or die made on a semiconductor wafer.

According to one aspect of the invention, there is a computer program comprising instructions that, when executed on at least one processor, cause at least one processor to control the apparatus to execute the method according to any one of claims 1-19. Provided.

According to one aspect of the invention, the carrier comprising the computer program of claim 16, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, or a non-temporary computer-readable storage medium. There is a carrier offered.

According to one aspect of the invention, an apparatus for determining in-plane strain (IPD) of a substrate comprising a plurality of patterned regions, spanning one of a plurality of patterned regions on the substrate. Intra-regional data showing local stress distribution is acquired, inter-regional data showing stress distribution across multiple substrates is determined based on the intra-regional data, and IPD of the entire substrate is determined based on the inter-regional data. Equipment is provided.

According to one aspect of the present invention, there is provided a lithography apparatus including the apparatus according to claim 22.

According to one aspect of the present invention, there is provided a lithography cell including the lithography apparatus according to claim 23.

Next, an embodiment of the present invention will be described as an example with reference to the attached schematic diagram.

The outline of the lithography apparatus is shown. The outline of the lithography cell is shown. Schematic representation of holistic lithography representing cooperation between three key technologies for optimizing semiconductor manufacturing. An exemplary step for exposing a patterned area on a substrate is shown. An example of a local in-field stress that causes a higher order distortion pattern throughout the substrate is shown schematically. It is schematically shown that the higher-order inter-field IPD of the processed wafer can be determined by subtracting the average IPD of each field from the measured IPD of the processed wafer. Schematic representation of the use of constant top film strain and linear top film strain in FEM to determine IPD and OPD. It is a flow diagram which shows the method for determining the IPD of the whole substrate.

Generally disclosed herein are methods and devices for determining the IPD of the entire substrate. In an exemplary configuration, this determines the intra-field (or intra-regional) stress data that specifies the local stress distribution across the field, and based on the intra-field stress data, specifies the stress distribution across the field. It can be achieved by determining the inter-field stress data for the fields of. The IPD can then be determined based on the inter-field stress data.

As used herein, the terms "radiation" and "beam" refer to ultraviolet light (eg, wavelengths of 365, 248, 193, 157, or 126 nm), and EUV (eg, poles having wavelengths in the range of about 5-100 nm). Used to include all types of electromagnetic radiation, including (ultraviolet).

As used herein, the terms "reticle," "mask," or "patterning device" correspond to the patterns created on the target portion of the substrate and can be used to give the incident radiation beam a patterned cross section. It can be broadly interpreted as referring to a general patterning device. The term "light bulb" is also used in this context. In addition to classic masks (transmissive or reflective, binary, phase shift, hybrid, etc.), other examples of such patterning devices include programmable mirror arrays and programmable LCD arrays.

FIG. 1 schematically shows a lithography apparatus LA. The lithography device LA comprises an irradiation system (eg, also referred to as an irradiator) IL configured to adjust the radiation beam B (eg, UV radiation, DUV radiation or EUV radiation) and a patterning device (eg, mask) MA. A mask support (eg, mask table) MT connected to a first positioner PM constructed to support and configured to accurately position the patterning apparatus MA according to specific parameters, and a substrate W (eg, resist coat). Radiation beam B by a substrate support WT configured to support the wafer) and connected to a second positioner PW configured to accurately position the substrate support according to specific parameters. Includes a projection system (eg, a refraction projection lens system) PS configured to project a pattern given to the target portion C.

During operation, the irradiation system IL receives a radiation beam from the radiation source SO via the beam delivery system BD. The irradiation system IL has a variety of refraction, reflection, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof, for directing, shaping, and / or controlling radiation. Can include various types of optical components. The irradiator IL can be used to adjust the radiation beam B to have the desired spatial and angular intensity distribution in a plane cross section of the pattern forming apparatus MA.

As used herein, the term "projection system" PS refers to refraction, reflection, suitable for exposure due to the radiation used and / or other factors such as the use of immersion liquid and the use of vacuum. It should be broadly construed to include various types of projection systems, including reflective refraction, anamorphosis, magnetic, electromagnetic and / or electrostatic optical systems, or any combination thereof. The use of the term "projection lens" herein can be considered synonymous with the more general term "projection system" PS.

The lithography apparatus LA is also called immersion lithography, in which at least a part of the substrate can be covered with a liquid having a relatively high refractive index, for example, water so as to fill the space between the projection system PS and the substrate W. Can be Details of the immersion technique are described in US6952253 and are incorporated herein by reference.

The lithography apparatus LA can also be of the type having two or more substrate supports WT (also referred to as "dual stage"). In such a "multi-stage" machine, the substrate support WT can be used in parallel and / or steps in preparation for subsequent exposure of the substrate W can be performed on the substrate W disposed on one side of the substrate support WT. Can be done with. The substrate W on the other substrate support WT is used to expose the pattern on the other substrate W.

In addition to the substrate support WT, the lithography apparatus LA may include a measurement stage. The measurement stage is configured to hold the sensor and / or the cleaning device. The sensor can be arranged to measure the characteristics of the projection system PS or the characteristics of the radiation beam B. The measurement stage can hold a plurality of sensors. The cleaning device can be configured to clean part of the lithography system, such as part of the projection system PS or part of the system that provides the immersion liquid. The measurement stage can be moved under the projection system PS when the board support WT is away from the projection system PS.

During operation, the radiation beam B is incident on a patterning device (for example, a mask held by the mask support MT) and is patterned by a pattern (design layout) existing on the patterning device MA. After passing through the mask MA, the radiation beam B passes through the projection system PS, which focuses the beam on the target portion C of the substrate W. The substrate support WT moves precisely, for example, to place different target portions C in the path of the radiation beam B at focused and aligned positions with the help of a second positioner PW and a positioning system IF. The substrate supports the WT so that it does. Similarly, a first positioner PM and possibly another position sensor (not explicitly shown in FIG. 1) are used to accurately position the patterning device MA with respect to the path of radiation beam B. be able to. The patterning device MA and the substrate W are aligned using the mask alignment marks M1 and M2 and the substrate alignment marks P1 and P2. Although the illustrated substrate alignment marks P1 and P2 occupy a dedicated target portion, they may be placed in the space between the target portions. The substrate alignment marks P1 and P2 are known as scribe lane alignment marks when they are arranged between the target portions C.

As shown in FIG. 2, the lithographic apparatus LA can form part of a lithography cell LC, also called a lithography cell or (litho) cluster, and can also perform pre-exposure and post-exposure processes on the substrate W. Often included. Conventionally, these include a spin coater SC for depositing a resist layer, a developer DE for developing an exposed resist, a chill plate CH and a bake plate BK, and a W for adjusting the temperature of a substrate (for example, a resist). (For layer conditioning solvent) is included. The board handler or robot RO picks up the board W from the input / output ports I / O1 and I / O2, moves them between different process devices, and sends the board W to the loading bay LB of the lithography device LA. The devices in the lithocell are often collectively referred to as tracks and are usually under the control of the track control unit TCU, and the track control unit TCU itself is a monitoring control system that controls the lithography device LA via, for example, the lithography control unit LACU. It can be controlled by SCS.

In order for the substrate W exposed by the lithography device LA to be exposed correctly and consistently, the substrate is inspected and patterned structures such as overlay errors, line thickness, critical dimensions (CD) between subsequent layers. It is desirable to measure the characteristics of. For this purpose, an inspection tool (not shown) may be included in the lithocell LC. Others performed on subsequent exposures or unprocessed substrate exposures or substrate Ws if an error is detected, especially if the inspection is performed before the other substrate W in the same batch or lot is inspected. Adjustments can be made to the processing steps of.

Using an inspection device, also known as a metric tool, how the characteristics of the substrate W, in particular the characteristics of different substrates W, vary from layer to layer, or how the characteristics associated with different layers of the same substrate W are. Determine if it changes to. Alternatively, the inspection device may be constructed to identify defects on the substrate W and may be, for example, part of a lithocell LC, integrated into a lithography device LA, or even a stand-alone device. The inspection device may be a latent image (an image of the resist layer after exposure) or a semi-latent image (an image of the resist layer after baking step PEB after exposure), or a developed resist, or an image (exposed portion or non-exposed part of the resist). The characteristics of the image (after the pattern transfer step such as etching) or the etched image (after the pattern transfer step such as etching) can be measured.

Generally, the patterning process in the lithography apparatus LA is one of the most important steps in a process that requires high accuracy in sizing and arranging the structure on the substrate W. To ensure this high accuracy, the three systems can be combined as a so-called "overall" control environment, as schematically shown in FIG. One of these systems is a lithography apparatus LA that is (virtually) connected to the Mettrositool MT (second system) and the computer system CL (third system). The key to such an "overall" environment is optimizing the coordination between these three systems, strengthening the entire process window, providing a tight control loop, and the patterning performed by the lithography device LA. Try to stay within the process window. The process window defines a range of process parameters (eg, dose, focus, overlay) that produce a defined result (such as a functional semiconductor device) for a particular manufacturing process, usually within that range of the lithography process. Alternatively, changes in the process parameters of the patterning process are allowed.

The computer system CL uses (part of) the patterned design layout to predict the resolution enhancement technology to be used, perform computational lithography simulations and calculations, and which mask layout and lithography equipment settings are in the patterning process. It is possible to determine whether to achieve the maximum overall process window (indicated by the double arrow in the SCI of the first scale in Figure 3). Typically, the resolution enhancement technique is arranged to match the patterning potential of the lithography apparatus LA. The computer system CL is used to detect where the lithography device LA is currently operating in the process window (eg, using the input from the Mettrosi tool MET), for example, non-optimal processing (using the input from the Mettrosi tool MET). In FIG. 3, it is also possible to predict whether a defect (indicated by the arrow pointing to the “0” of the second scale SC2) may be present.

The METROGI TOOL MET provides inputs to the computer system CL to enable accurate simulation and prediction, and possible drifts, such as the calibration status of the lithography equipment LA (third in FIG. 3). Feedback can be provided to the lithography apparatus LA to identify (indicated by multiple arrows on the scale SC3).

FIG. 4 shows an exemplary step for exposing a patterned region (eg, a die) on a substrate W in the dual stage apparatus of FIG. First, the process according to the conventional method will be described. The present disclosure is not limited to the type of dual stage device exemplified. Those skilled in the art will appreciate that similar operations can be performed on other types of lithography equipment, such as those with a single substrate stage and docking metric stage.

The left side of the dotted box shows the steps performed at the measurement station MEA, and the right side shows the steps performed at the exposure station EXP. From time to time, the substrate table WT is at the exposure or measurement station. The exposure station and the measurement station can be located in the same place. In an exemplary arrangement, there are two wafer tables, each carrying substrates W and W'. For the purposes of this description, it is assumed that the substrate W has already been loaded into the exposure station.

In step 200, the second substrate W'is loaded into the device by a mechanism not shown. These two substrates are processed in parallel to improve the throughput of the lithography equipment.

With reference to the first newly loaded substrate W', this can be a previously unprocessed substrate prepared with a new photoresist for the first exposure in the apparatus. However, in general, the described lithography process is only one step in a series of exposure and processing steps, so the substrate W'has already passed through this device and / or other lithographic devices several times. , There may be processing to be carried out in the future. Especially for issues that improve overlay performance, the task is to ensure that the new pattern is applied to the exact correct position on the board where one or more cycles of patterning and processing have already taken place. Each patterning step can result in misalignment of the applied pattern, but subsequent processing steps IPD the substrate and / or the pattern applied to the substrate to achieve satisfactory overlay performance. It gradually brings about distortion such as.

The previous and / or subsequent patterning steps can be performed on other lithographic devices, as just described, and even different types of lithographic devices. For example, some layers of a device manufacturing process that require more parameters such as resolution and overlays can be performed with more sophisticated lithography tools than others that require less. Therefore, some layers may be exposed with an immersion type lithography tool and others with a "dry" tool. Some layers may be exposed with tools operating at DUV wavelengths and others may be exposed using EUV wavelength radiation. Some layers can be patterned by steps that are alternatives or supplements to exposure in the illustrated lithographic device. Supplementary techniques for such alternatives include, for example, imprint lithography, self-aligned multiple patterning, and directed self-organization. Similarly, other processing steps performed layer by layer (eg, CMP and etching) may be performed on different devices for each layer.

In 202, an alignment measurement using the substrate mark P1 and the like and an image sensor (not shown) is used to measure and record the alignment of the substrate with respect to the substrate table WT. In addition, some alignment marks across the substrate W'are measured using the alignment sensor AS. These measurements, in one embodiment, are used to establish a substrate model (sometimes referred to as a "wafer grid") and are very accurate in the distribution of marks throughout the substrate, including distortions against a nominal rectangular grid. Map to.

In step 204, geometric properties such as a map of wafer height (Z) relative to the XY position are measured using the level sensor LS. Primarily, height maps are only used to achieve accurate focusing of exposed patterns. Furthermore, it may be used for other purposes.

When the substrate W'is loaded, it receives recipe data 206 that also defines the exposure to be performed, as well as the characteristics of the wafer and the patterns previously created and created on it. If there are alignment mark options on the board and alignment sensor configuration options, these selections are defined in the alignment recipe in recipe data 206. Therefore, the alignment recipe defines how to measure the position of the alignment mark and which mark to measure.

At 210, the wafers W'and W are exchanged, and as a result, the measured substrate W'becomes a substrate W that enters the exposure station EXP. In step 212, reticle alignment is performed using the mask alignment marks M1 and M2. At steps 214, 216 and 218, scanning motion and radiating pulses are applied to successive target positions across the substrate W to complete the exposure of some patterns.

By using the alignment data and height maps obtained at the measurement station in performing the exposure step, these patterns are accurately aligned with respect to the desired location, especially with respect to previously placed features on the same substrate. Will be done. The exposed substrate, now labeled W', is unloaded from the device in step 220 and undergoes etching or other processes according to the exposed pattern.

Substrate distortion can affect the overlay performance of the lithography process. Substrate distortion can result from substrate heat treatment (such as laser annealing) or the deposition of stressed thin films. The free-form substrate shape that can be measured with the offline metering tool can change as a result of this distortion. Typical shapes that can be observed in mass production are the shapes of bowls (concave), umbrellas (convex), and saddles. Deviations from these shapes result in higher in-plane distortion. In most cases, these in-plane distortions are slowly spatially changing functions that can be captured by existing alignment models such as (eg) higher order wafer alignment (HOWA) models. Another approach is to use free-form substrate shape measurements. If the relationship between the free-form substrate shape and the in-plane distortion after clamping is known or can be modeled, predictions (and modifications) can be made to improve overlay performance.

In-plane distortion becomes more difficult to predict if the stress distribution changes as a function of substrate position, or if the stress layer also deposits on the backside of the substrate. As a particular example, a non-uniformly stressed thin film layer (eg, silicon nitride) can be deposited on both the front and back surfaces of the substrate. These films may be sufficiently similar so that the free-form substrate shape remains flat. In such a case, in-plane distortion cannot be predicted from the free-form substrate shape measurement. It is also difficult to capture in-plane distortion using a suitable alignment model because the stress distribution is too high to capture properly and / or there may be sharp transitions. This can occur if there are both patterned and unpatterned (such as edges) fields on the substrate. In addition, the processing fingerprint can compete with the stress fingerprint, for example due to deformation of the alignment marks.

We understand that local in-field stresses can cause higher order distortion patterns throughout the substrate. Specifically, the stress in the field may cause higher-order IPD in the entire substrate.

FIG. 5 shows a change (out-of-plane deviation) in the free-form wafer shape due to processing. Alignment marks are etched on the substrate 300 such as a semiconductor wafer. The wafer is read by a wafer shape measuring tool to determine the OPD wafer shape 302 (gray level indicates deviation of the wafer surface from the nominal value). In this case, since the diameter of the wafer is 300 mm, the X and Y coordinates are scaled in the range of −150 to +150 mm (see FIG. 5). To create a distortion pattern on the wafer 300, a stressed nitride layer is deposited on the wafer and re-etched from each field to include a plurality of nitride-covered regions 306. The resulting wafer 304 is produced, which results in local internal stress. Further, the impact 310 of the stress layer on the wafer shape is shown in FIG. The processed wafer 304 is read again by the wafer shape measuring tool to determine the OPD wafer shape 308. The processed induction wafer OPD deformation 310 can be separated by subtracting the processed OPD wafer shape 308 from the unprocessed OPD wafer shape 302.

The IPD 400 resulting from the processed wafer 304 due to the higher order inter-field IPD is shown in FIG. As shown in FIG. 6, the higher-order inter-field IPD 400 of the processed wafer 304 can be determined by subtracting the average IPD 402 of each field from the measured IPD 404 of the processed wafer 400. The measured IPD 404 of the processed wafer 304 due to the deposition of nitrides and partial removal from each field contains important in-field components. Even if the average field IPD 402 is removed from the measured IPD 404, a fairly high order inter-field IPD pattern 400 remains, as clearly shown in the wafer plot on the right side of FIG. Higher-order inter-field IPD patterns appear primarily towards the wafer edge. However, at the 3: 406 and 9: 408 positions, higher order inter-field IPDs are also important in the inner wafer region. Simulations have confirmed that higher-order inter-field distortion patterns are actually introduced by the in-field stress patterns. Higher-order inter-field IPDs were calculated by assuming uniform stripes of nitride on top of the wafer using the finite element method (FEM) and showed a pattern similar to the measurement.

In known arrangements, for a set of predefined polynomial top film strains, the OPD (freeform substrate shape) and post-chucking IPD are determined using the finite element method (FEM). For example, and as shown in FIG. 7, constant top film strains 500 and linear top film strains 502 can be used, if desired, in the same manner as other predefined top film strains. This creates a library of OPDs and corresponding IPDs when chucking such substrate shapes. You only need to create the library once.

After the library is created, the OPD shape of the substrate is measured and fitted to the OPD from the predefined top film polynomial strains in the library. In an exemplary configuration, the fit may include multiple weighted OPDs from the library. The fit weight can be used as a factor to reconstruct the film strain at the top.

If the top film strain is known, the same coefficients can be used to construct the IPDs obtained after chucking by summing the IPDs corresponding to the prestrains of each polynomial weighted with the same coefficients.

In order to have a unique relationship between the shape of the substrate and the strain of the top film, it is assumed that the strain of the top film has an isotropic thermal deformation structure (strain_x = straight_y, no shear).

This methodology can be used to predict IPD from wafer geometry. However, this method is not practically feasible when the secondary residuals of the free-form wafer shape are very high order, as in the case of inter-field distortion caused by in-field stress.

FIG. 8 shows a flow chart of a method for determining the IPD of the entire substrate. The substrate comprises a plurality of patterned areas (or dies or fields).

The in-field stress pattern is first determined, which specifies the local stress pattern within at least one of the plurality of patterned regions. In one exemplary configuration, the in-field stress pattern can be determined based on geometric properties such as the OPD shape of the substrate. That is, the measurements can be made to determine the height profile of the substrate 600. The quadratic derivative of the height profile of the substrate can be determined in proportion to the distribution of stress on the substrate 602. Following this, the average quadratic derivative over each of the plurality of patterned regions can be determined based on the quadratic derivative of the height profile 604. The average quadratic derivative is an estimate of the in-field stress pattern for each patterned region.

The average quadratic derivative of the height profile is assigned 606 to two or more of the plurality of patterned regions.

The IPD and OPD of the substrate are determined using the finite element method using the average quadratic derivative assigned to the patterned region, which indicates the stress in the field. The determined IPD includes both the in-field IPD and the above-mentioned higher-order inter-field IPD.

Determined IPDs and OPDs for substrates containing both in-field IPDs and higher-order inter-field IPDs are added to the above library for IPD determination based on OPD substrate geometry.

By adding IPDs and OPDs related to in-field stresses to the library, substrate shape-based IPD prediction can be enabled even when the IPDs (inter-fields) induced by in-field stresses are of very high order. ..

In another exemplary configuration, the in-field data can be inferred from the layout data associated with the patterned area. Layout data can be determined based on one or more of field layouts, die layouts, chip layouts, or reticle layouts. Alternatively, or in addition, in-field stress data can be determined based on the material properties of the substrate and / or the material properties of the features produced on the substrate and forming the pattern of the patterned regions. Alternatively, or in addition, stress data in the field can be determined based on data related to the stack of features that form at least part of the pattern. Alternatively, or in addition, in-field stress data may be determined based on measurements of in-plane displacement of one or more features forming at least a portion of the pattern.

Based on layout and / or material properties, stress data in the field can be determined based on modeling that will be understood by those of skill in the art.

Further embodiments of the invention are disclosed in the list of embodiments numbered below.

1. 1. A method for determining in-plane distortion (IPD) of an entire substrate that includes multiple patterned regions.
Obtain intra-regional data showing the local stress distribution over one of multiple patterned regions.
Based on the intra-regional data, determine the inter-regional data showing the overall stress distribution of the entire substrate.
A method of determining the IPD of the entire substrate based on the inter-regional data.
2. 2. The method of embodiment 1, further comprising acquiring intra-regional data based on the measurement of one or more geometric properties of the substrate.
3. 3. 2. The method of embodiment 2, wherein the measured geometric properties include the out-of-plane shape of the substrate.
4. 8. The method of embodiment 2 or 3, wherein acquiring intra-regional data further comprises determining a quadratic derivative of one or more measured geometric properties.
5. Determining the quadratic derivative of one or more measured geometric properties determines the quadratic derivative of one or more geometric properties measured along a particular planar direction. And / or the method according to embodiment 4, comprising determining a measured mixed quadratic derivative along one or more geometric properties along two non-planar directions. ..
6. 8. The method of embodiment 4 or 5, wherein retrieving intra-regional data further comprises averaging a determined quadratic derivative over a plurality of patterned regions.
7. A method according to any preceding embodiment in which intra-regional data is acquired based on the layout of patterns within the patterned region.
8. 7. The method of embodiment 7, wherein the layout of the pattern is determined based on one or more of a field layout, a die layout, a chip layout, and a reticle layout.
9. 8. The method of embodiment 7 or 8, wherein intra-regional data is acquired based on material properties and / or pattern features associated with the substrate.
10. The method of any of embodiments 7-9, wherein intra-regional data is acquired based on data related to a stack of features that form at least a portion of the pattern.
11. The method of any of embodiments 7-10, wherein in-region data is acquired based on measurements of in-plane displacement of one or more features that form at least a portion of the pattern.
12. The method according to any of the preceding embodiments, wherein the inter-regional data is determined based on the intra-regional data using the finite element method.
13. 12. The method of embodiment 12, further comprising determining out-of-plane distortion (OPD) and IPD based on intra-regional data using the finite element method.
14. 13. The method of embodiment 13, further comprising adding OPDs and IPDs determined based on the results of the finite element method to a library containing multiple OPDs for IPDs for a set of predefined top film stresses. ..
15. The method according to embodiment 14, further comprising determining the IPD of an additional substrate based on the geometric properties of one or more of the additional substrates and the measurement of OPD and IPD in the library.
16. One or more geometric properties of the additional substrate include the OPD shape of the additional substrate.
Determining the IPD of an additional substrate is based on adapting the OPD shape of the additional substrate to one or more of the multiple OPDs in the library, and the IPD corresponding to one or more of the multiple OPDs. 15. The method of embodiment 15, comprising determining the IPD.
17. Determining the IPD of an additional substrate involves adapting the OPD shape of the additional substrate to multiple OPDs in the library, each of which is weighted in the conformance.
16. The method of embodiment 16, wherein determining the IPD comprises summing the IPDs corresponding to the plurality of OPDs in the fit, weighted based on the weights of the plurality of OPDs.
18. Any prior implementation, further comprising one or both of applying the correction to the lithography equipment based on the determined IPD and controlling the alignment of the substrate in the lithography equipment based on the determined IPD. Morphological method. 19. The method according to the preceding embodiment, wherein the region comprises a field or die made on a semiconductor wafer.
20. A computer program comprising instructions that, when executed on at least one processor, cause at least one processor to control the device and perform any of the methods according to embodiments 1-19.
21. A carrier in which the computer program of embodiment 20 is housed, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, or a non-temporary computer-readable storage medium.
22. A device for determining in-plane strain (IPD) of a substrate containing multiple patterned regions.
Intraregional data showing local stress distribution over one of multiple patterned regions on the substrate was acquired.
Based on the intra-regional data, determine the inter-regional data showing the stress distribution across multiple substrates.
A device that determines the IPD of the entire board based on inter-regional data.
23. A lithography apparatus including the apparatus according to the twenty-second embodiment.
24. A lithography cell including the lithography apparatus according to the 23rd embodiment.

Although herein specifically refers to the use of lithographic devices in the manufacture of ICs, it should be understood that the lithographic devices described herein may have other uses. Other possible applications include the manufacture of integrated optical systems, magnetic domain memory guidance and detection patterns, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, and the like.

Although embodiments of the invention can be specifically referred to herein in the context of lithographic equipment, embodiments of the invention can be used in other equipment. Embodiments of the invention may form part of a mask inspection device, a mettologi device, or any device that measures or processes an object such as a wafer (or other substrate) or mask (or other patterning device). can. These devices are commonly referred to as lithography tools. Such lithography tools can use vacuum or ambient (non-vacuum) conditions.

Although specific references have been made above to the use of embodiments of the invention in the context of optical lithography, where the context allows, the invention is not limited to optical lithography and may be used in other applications such as imprint lithography. It will be understood that it can be done.

Those skilled in the art will be able to envision other embodiments without departing from the appended claims.

Claims (15)

A method for determining in-plane distortion (IPD) of an entire substrate that includes multiple patterned regions.
Obtain intra-regional data showing the local stress distribution over one of multiple patterned regions.
Based on the intra-regional data, determine the inter-regional data showing the overall stress distribution of the entire substrate.
A method of determining the IPD of the entire substrate based on the inter-regional data. The method of claim 1, further comprising acquiring intra-regional data based on the measurement of one or more geometric properties of the substrate. The method of claim 2, wherein the measured geometric properties include the out-of-plane shape of the substrate. The method of claim 2 or 3, wherein retrieving intra-regional data further comprises determining a quadratic derivative of one or more measured geometric properties. Determining the quadratic derivative of one or more measured geometric properties determines the quadratic derivative of one or more geometric properties measured along a particular planar direction. The method of claim 4, comprising determining a mixed quadratic derivative of one or more geometric properties along two directions that are not parallel to the plane and / or measured. The method of claim 4 or 5, wherein retrieving intra-regional data further comprises averaging a determined quadratic derivative over a plurality of patterned regions. The method according to any one of claims 1 to 6, wherein the intra-regional data is acquired based on the layout of the pattern in the patterned region. 7. The method of claim 7, wherein the layout of the pattern is determined based on one or more of a field layout, a die layout, a chip layout, and a reticle layout. The method of claim 7 or 8, wherein the intra-regional data is acquired based on the material properties and / or pattern features associated with the substrate. The method according to any one of claims 7 to 9, wherein the intra-regional data is acquired based on the data related to the stack of features forming at least a part of the pattern. The method of any one of claims 7-10, wherein in-region data is acquired based on the measurement of in-plane displacement of one or more features forming at least a portion of the pattern. The method according to any one of claims 1 to 11, wherein the inter-regional data is determined based on the intra-regional data using the finite element method. 12. The method of claim 12, further comprising determining out-of-plane distortion (OPD) and IPD based on intra-regional data using the finite element method. 13. The method of claim 13, further comprising adding OPDs and IPDs determined based on the results of the finite element method to a library containing multiple OPDs for IPDs for a set of predefined top film stresses. .. Claims 1-14 further include applying corrections to the lithography equipment based on the determined IPD and / or controlling the alignment of the substrate in the lithography equipment based on the determined IPD. The method according to any one of the above.

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